In terms of conventional bicycles, two manners of connecting a disc brake caliper 400 to a front fork 500 are shown in FIG. 7 and FIG. 8. Please refer to FIG. 7. Each bottom end of the two fork legs 510 of the front fork are connected to two ends of a hub 200, respectively. A disk brake rotor 300 has a center which is coaxially connected to one end of the hub 200. One of the fork legs 510 is closer to the disk brake rotor 300 than the other fork leg 510. The fork leg 510 closer to the disk brake rotor 300 has two mounting flanges 520 protruding out from a back surface of the fork leg 510. An interval is between the two mounting flanges 520. A connecting seat 600 is connected and fixed to the mounting flanges 520 by bolts or screws B penetrating through the connecting seat 600 and the mounting flanges 520 along a direction parallel to an axial direction of the hub 200. The disc brake caliper 400 is connected and fixed to the connecting seat 600 so that the disc brake caliper 400 is connected to the mounting flanges 520. A brake hose 410 is connected to the disc brake caliper 400.
Next, please refer to FIG. 8, a structure of the front fork assembly in FIG. 8 is similar to a structure of the front fork assembly in FIG. 7. The difference between the structure of the front fork assembly in FIG. 8 and the structure of the front fork assembly in FIG. 7 is that bolts or screws B penetrate through the connecting seat 600 and the mounting flanges 520 along a direction parallel to a radial direction of the hub 200. The disc brake caliper 400 is connected and fixed to the connecting seat 600 so that the disc brake caliper 400 is connected to the mounting flanges 520.
The disc brake calipers 400 in FIG. 7 and FIG. 8 are located on an outer surface of the fork leg 510 of the front fork 500. The volume of the disc brake calipers 400 protruding out from the outer surface of the fork leg 510 is too large such that an air resistance is generated when the bicycle is ridden by rider. Moreover, the disc brake caliper 400 is easily damaged or the fixing structure between the disc brake caliper 400 and the fork leg 510 may become loose by an external impact, and therefore this affects braking. In addition, the shape of disc brake caliper 400 protruding out from the outer surface of the fork leg 510 has no aesthetic feeling for consumers.